The European Commission has closed an investigation into the rough diamond market, on the basis of increased transparency in De Beers' distribution arrangements, known as Supplier of Choice (SOC). At the Commission's request, De Beers, the world's largest rough diamond producer, has revised the mandate for the Supplier of Choice Ombudsman, who safeguards the objectivity of the SOC distribution system. The revised mandate of the Ombudsman will allow enhanced transparency in the selection of De Beers' customers (major diamond cutting firms know as "sightholders") and in the allocation of diamonds and will therefore enhance competition on the worldwide rough diamond market. This complements an earlier decision addressed to De Beers in 2006 to end rough diamond purchases from its principal competitor ALROSA by the end of 2008.